Kall-Su was the son of a human woman, and an unknown father (though suggested to have been an Ice-Dragon in human form.) Kall-Su was feared and hated by the people of his mother's village, and was ostracized. Eventually, after several years of this, Kall-Su's mother attempted to kill him using the magic sword the Ice Falchion, believing its power would inhibit his healing abilities. Kall-Su survived, and instinctively used his magical abilities to kill his mother, and then the village which had drove her to murder. He was soon after found by Dark Schneider who was accompanied by Arshes Nei who was still a child at the time.

DS raised Kall-Su, teaching him magic alongside Arshes Nei, though his gifts were soon discovered to be a mirror image of Dark Schneider's as they focused on Ice and cold, whereas DS's focused on Fire. Eventually, DS told Kall-Su that he was to act as Dark Schneider's other half, as DS was missing a part of himself and was searching for it,

Kall-Su is first introduced alongside other riders leading a demon army. As Orge tells him the castle Judas has surrendered, Kall-Su smirks and refers to them as wimps and questions whether the royal family had the greatest army in the world. Gara asks him whether he remembers 15 years ago when the four of them and Dark Schneider were there to burn down the kingdom. The Ogre also tells him that while they were camping, Norman the Sorcerer was killed by someone, though they are not certain of who did it. As the Ogre briefly mentions that he was killed with Venom, Kall-Su tells him that it is impossible as Venom died with Dark Schneider on that day, 15 years ago.

Kall-Su is the greatest known master of Ice Magic, being able to envelope entire cities in a mountain of ice with a single spell. He is also familiar enough with Air Magic to cast Raven. However, he is suggested to not know any spells of Fire.

Kall-Su also has a superhuman healing factor, allowing him to survive injuries that would kill a normal human being.